The present invention relates to an image processing system for performing gradation modulation and rotation of bit map data having the attribute of rotation.
The quantity of data in an image used in a printer has increased with the advance of coloration, resolution and gradation in recent years. On the other hand, print data have been often requested to be rotated in accordance with the needs for printing two pages on opposite sides of one sheet of paper, printing a plurality of pages on one sheet of paper, etc. Hence, the demand for increase of the speed of rotation on such a large quantity of data has become greater.
A background-art image processing system for performing gradation modulation and rotation of bit map data having the attribute of rotation will be described with reference to FIG. 13.
As shown in FIG. 13, a background-art rotating system 10 generated a bit map rotated modulated output in accordance with a request given from a CPU through the steps of: once storing a bit map data input in a storage memory 13; rotating the data by rotating means 11 before gradation modulation; writing the rotated data back into the storage memory 13; modulating the gradation of the data by gradation modulating means 12; and writing the modulated data back into the storage memory 13.
A large capacity of memory was, however, required for the background-art gradation modulation and rotation of bit map data having the attribute of rotation because the data was rotated before gradation modulation. Hence, increase of the processing time was brought about.
Therefore, an object of the present invention is to provide an image processing system which can perform gradation modulation and rotation of bit map data at a high speed in spite of a small memory capacity.
In order to achieve the above object, according to an aspect of the present invention, an image processing system is configured to have: threshold table selecting means for selecting one of a plurality of threshold reference tables in accordance with an angle of rotation for bit map data having an attribute of rotation to thereby generate a threshold; gradation modulating means for performing gradation modulation by use of the threshold generated by the threshold table selecting means to thereby obtain gradation-modulated data; buffer means having a plurality of buffers and for storing the gradation-modulated data of the gradation modulating means into the plurality of buffers; addressing means for designating respective storage addresses for the plurality of buffers of the buffer means; rotating means for rotating the gradation-modulated data; and storage means for storing contents of the buffer means into the addresses designated by the addressing means and outputting the gradation-modulated data rotated by the rotating means.
Owing to the above configuration, the gradation modulation and rotation of bit map data can be performed at a high speed in spite of a small memory capacity.
Further, according to another aspect of the present invention, an image processing system is configured to have: threshold generating means for generating a threshold while controlling generation of a threshold reference table address in accordance with an angle of rotation for bit map data having an attribute of rotation; gradation modulating means for performing gradation modulation by use of the threshold generated by the threshold generating means to thereby obtain gradation-modulated data; buffer means having a plurality of buffers and for storing the gradation-modulated data obtained by the gradation modulating means into the plurality of buffers; addressing means for designating respective storage addresses for the plurality of buffers of the buffer means; rotating means for rotating the gradation-modulated data; and storage means for storing contents of the buffer means into the addresses designated by the addressing means and outputting the gradation-modulated data rotated by the rotating means.
Owing to the above configuration, the gradation modulation and rotation of bit map data can be performed at a high speed in spite of a small memory capacity.
The present invention provides an image processing system having: threshold table selecting means for selecting one of a plurality of threshold reference tables in accordance with an angle of rotation for bit map data having an attribute of rotation to thereby generate a threshold; gradation modulating means for performing gradation modulation by use of the threshold generated by the threshold table selecting means to thereby obtain gradation-modulated data; buffer means having a plurality of buffers and for storing the gradation-modulated data of the gradation modulating means into the plurality of buffers; addressing means for designating respective storage addresses for the plurality of buffers of the buffer means; rotating means for rotating the gradation-modulated data; and storage means for storing contents of the buffer means into the addresses designated by the addressing means and outputting the gradation-modulated data rotated by the rotating means. Accordingly, the apparatus has a function and operation that the gradation modulation and rotation of bit map data can be performed at a high speed in spite of a small memory capacity.
Further, the present invention provides an image processing system having: threshold generating means for generating a threshold while controlling generation of a threshold reference table address in accordance with an angle of rotation for bit map data having an attribute of rotation; gradation modulating means for performing gradation modulation by use of the threshold generated by the threshold generating means to thereby obtain gradation-modulated data; buffer means having a plurality of buffers and for storing the gradation-modulated data obtained by the gradation modulating means into the plurality of buffers; addressing means for designating respective storage addresses for the plurality of buffers of the buffer means; rotating means for rotating the gradation-modulated data; and storage means for storing contents of the buffer means into the addresses designated by the addressing means and outputting the gradation-modulated data rotated by the rotating means. Accordingly, the apparatus has a function and operation that the gradation modulation and rotation of bit map data can be performed at a high speed in spite of a small memory capacity.